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The Waterfall model is a widely used method of systems development. It consists of six major phases which occur in accordance with the sequence shown below:

The first step is planning. This is key as it defines the objectives of the project via the formation of a Baseline Project Plan (BPP) and aProject Scope Statement (PSS). The planning phase also lays out the activities to be undertaken in order to produce the system as intended. The waterfall model does not allow for regression so if an error occurs it must either be accepted or the project be abandoned.

The analysis stage involves evaluating the current system and taking into account the requirements of the users to ensure that the system developed will be an improvement on the existing system.

The design phase is essential in establishing how exactly the new system will operate. It can be split into two sub-divisions as shown above. Logical design deals with the way in which the data is to flow whilst the physical design is concerned with how the data is inputted, processed, stored and outputted.

Implementation finally produces a working system through different methods of coding, testing and installation. In order for users to operate the system correctly, training must take place. Documentation is an important task at this stage also and can be quite time consuming. It is for this reason that it is sometimes overlooked.

The final step is maintenance and this must take place on a regular basis in order for the system to continually provide a service of a certain standard.

Some of the major advantages of the waterfall model would be it’s simplicity. It’s linear structure makes it easy to follow and ensures that all prerequisites are taken prior to advancement. It works well with well-defined projects. The system is quite manageable and testing takes place at each stage.

There are however some disadvantages also. If the scope of a project is incorrectly decided upon it may become near-impossible to amend. As well as this, there is no usable software produced until very late in the process which means that a lot of time, effort and money must go in before one even knows if the result is worth the expenditure. It is for this reason also that the system is believed to be quite precarious.